Tag Archive for: gut health and microbiome

The brain is often talked about as the master of the body. It sends messages along the information superhighway of the central nervous system. This turns electric impulses and thoughts into action and behavior. The brain is like the Wizard of Oz: it’s the ring leader behind the curtain, directing the cognitive processes and movements of the body.

However, in recent years, scientists have found that the brain doesn’t act as independently as once believed. Careful studies show there is another major player aside from the brain. And a curious one at that. In fact, this other player isn’t a sole entity at all, but rather trillions of microscopic ones. It’s a system of trillions of bacteria and other bugs, known as your gut microbiome.

Here’s another way to look at it: Say the brain is the CEO of the company known as your body. That would make your microbiome the extensive members of the company’s staff. Having a good, connected working relationship between employees and the CEO creates success. But just like a company run with zero input from its staff, a body run solely by the brain misses out on essential messages and signals that would contribute to an ideal functioning body.

To avoid such tyranny, the body has coevolved alongside intestinal bacteria and other bugs. This makes the relationship between the microbiome and the brain an intertwined one. It’s a mutually beneficial partnership based on regular communication between the brain and microbiome. The two speak through a variety of mechanisms to maintain the health and well-being of your body. This crosstalk between the two affects hunger, digestion, and satiety, as well as your immune and mental health.

In order to appreciate how your microbiome can affect your brain, let’s gain an understanding of the microbiome. Then we’ll look at how it works together with the brain. First, let’s focus on the bacteria and other bugs. To answer: What exactly lives in your gut and why?

The Microbiome: Your Body’s Bacteria And Other Bugs

Your gut is home to trillions of little bugs known collectively as the microbiome. These microorganisms (including bacteria, fungi, viruses, protozoa, and other bugs) make up the community that resides there.

Microbiota is often used interchangeably with microbiome. You’ll see the term microbiome used more here because it stands for much more than the bugs themselves. “Microbiome” encompasses the entire community of microorganisms along with their functionality and activity in the gut.

Many of the functionalities of your gut microbiome occur there, in your intestines. However, there are interactions between those bugs and other parts of the body that act as communication mechanisms between the microbiome and the brain. Let’s learn more about these interactions that make up the gut-brain axis.

Your Brain On Bugs—Gut-Brain Axis Basics

As mentioned before, your brain and microbiome constantly communicate. This link is often referred to as the gut-brain axis, or GBA. Communication along this line is essential to maintain homeostasis—or balance—in your gut and elsewhere. There are various routes of communication that constitute the GBA. But the most prominent is the vagus nerve. It’s involved in digestion and healthy gut immune response, among other bodily processes and reactions.


The vagus nerve is a cranial nerve that starts in the brainstem and runs down to the large intestine. This nerve covers so much ground within the body that it’s no surprise that the vagus nerve is responsible for regulating a number of internal functions. Some of these are digestion, respiratory rate, heart rate, blood pressure, some immune responses, and several internal reflexes (e.g., sneezing and swallowing).

Digestion is the first topic to chew on.

Research has shown that the gut isn’t just the site of digestion and nutrient absorption. The gut is also the mediator between its microbiome and the brain. Basically, the gut witnesses the processing of the food you consume. Then it reports relevant information from that process to the brain via the vagus nerve.

As the site of food digestion, the gut has immediate knowledge of what is being consumed. It gathers information about nutritional and energy content. The vagus nerve makes sure the brain stays up-to-date on this sensory information, like hunger cues and feelings of fullness.

This knowledge is important for the brain, so it can determine:

  1. How to drive related impulses (e.g., telling your brain your gut is full and therefore you should stop eating).
  2. How to shift your mood (e.g., if you’re hungry, your mood can become irritable).
  3. Where it is best to send energy (e.g., when you are cold, energy is sent to warm your most vital organs).

Relaying Immune Reflexes

The vagus nerve also communicates other gut events to the brain. Along with the ingested food comes allergens and other microbes that can activate normal immune responses in the gastrointestinal (GI) tract. Even though they are typical, healthy responses, these reactions can occasionally and temporarily get in the way of regular gut function.

Your brain needs to know about these minor inconveniences. So, this information is “sensed” by the gut and carried to the brain by the vagus nerve on the information superhighway of the gut-brain axis. The direction of information described above is referred to as an “afferent” pathway. That means messages travel away from the gut to the brain.

Gut-brain axis communication helps provide your brain—and eventually the rest of your body—with information it needs to mount and maintain a proper, healthy response. The communications from the brain to the gut are along what’s called “efferent” pathways (working in the opposite direction from the afferent pathways). They work when the efferent fibers from the brain send signals back down the vagus nerve to help maintain and support a healthy, normal immune response.

You Are What You Eat

It’s important to consider how to keep your gut and brain healthy in order to maintain quality communication between both along the gut-brain axis. The easiest way to do this is through food and nutrition. And you have at least three opportunities each day to influence what goes into your gut.

Your microbiome acts as a mediating factor between lifestyle choices—like diet—and the maintenance of health. What you eat enters your body and may alter the bacteria found in your gut. The effects of this can be positive or negative on processes like digestion. And changes to these processes can either maintain or hinder your health. Let’s take a closer look.

Diets rich in plant-based protein and fiber tend to increase the abundance of bacteria like Bifidobacteria and Lactobacillus. These are beneficial bacteria that tend to maintain health in your gut. Conversely, diets rich in animal-based protein and saturated fat could increase the abundance of Bacteroides and Alistipes, which are thought to be associated with cardiovascular and bowel issues.

Additionally, studies show that those who consume more vegetables and less fat tend to have a more diverse microbiome with many different beneficial bacteria represented. And those who consume a high-fat diet tend to lack bacterial diversity in the gut, which isn’t good for your digestive health.

While the community of bacteria within your gut is complex, keeping it healthy can be rather simple. Beneficial bacteria prefer to eat certain types of food that tend to get labeled as “healthy” or “healthier.” The opposite is true for bad bacteria: they prefer to eat the things you should eat in small amounts, like saturated fat. So, when you sit down to eat next, ask who you would rather feed—the good or the bad bacteria?

Here are some tips to consider:

  • Minimize your intake of saturated fats. Unsaturated fats like olive oil and avocados promote the healthier bacteria like Bifidobacteria and Saturated fats tend to increase Bacteroides, the bugs that negatively impact gut health.
  • Increase your intake of fiber-rich vegetables. These foods contain many complex starches and fiber your body can’t break down completely on its own. Instead, your body relies on the gut bacteria to break down some of the fiber. In the process, the bacteria create short-chain fatty acids that support gut health. These fiber-rich foods act like prebiotics, feeding your microbiome.
  • Consider adding probiotic foods to your diet. Probiotics support a healthy balance of beneficial bacteria to your gut. Find a tasty yogurt that you like, and keeping your gut healthy will feel like a sweet treat! If dairy isn’t your thing, you can try fermented foods like sauerkraut, kimchi, or sourdough. And probiotic supplements are also a great way to help you find a beneficial balance of gut bacteria.

Minding Your Microbiome

Your microbiome is a complex system that’s ready to help you live your best life. It does so largely through digestive processes, but also by relaying important messages to your brain. Maintaining a happy gut keeps communication along the gut-brain axis flowing. And together, this powerful pair helps support your overall health.

About the Author

Jenna Templeton is a health educator and freelance science writer living in Salt Lake City, Utah. After receiving a bachelor of science degree in chemistry from Virginia Tech, Jenna spent five years as a research scientist in the nutritional industry. This work fueled her interest in personal wellness, leading her to pursue a graduate degree in Health Promotion & Education from the University of Utah. Outside of work, Jenna enjoys live music, gardening, all things food, and playing in the Wasatch mountains.

Agusti A, Garcia-Pardo MP, et al. (2018). “Interplay Between the Gut-Brain Axis, Obesity, and Cognitive Function”. Frontiers in Neuroscience. 12: 155.

Carabotti M, Scirocco A, et al. (2015). “The gut-brain axis: interactions between enteric microbiota, central and enteric nervous systems.” Ann Gastroenterol. 28 (2): 203-209.

Bischoff SC. (2011). “‘Gut health: a new objective in medicine?’” BMC Medicine. 9: 24.

Breit S, Kupferberg A, et al. (2018). “Vagus Nerve as Modulator of the Brain-Gut Axis in Psychiatric and Inflammatory Disorders.” Frontiers in Psychiatry. 9: 44.

Foster JA, Rinaman L, Cryan JF. (2017). “Stress & the gut-brain axis: Regulation by the microbiome.” Neurobiology of Stress. 7: 124-136.

Houghteling PD, Walker WA. (2015). “Why is initial bacterial colonization of the intestine important to the infant’s and child’s health?” J Pediatr Gastroenterol Nutr. 60 (3): 294-307.

Hsiao E. (2013). “Mind-altering Microbes: How the Microbiome Affects Brain and Behavior”. TED Lecture.

Quigley EMM. (2013). “Gut Bacteria in Health and Disease.” Gastroenterol Hepatol. 9 (9): 560-569.

Singh RK, Chang H, et al. (2017). “Influence of diet on the gut microbiome and implications for human health.” J Transl Med. 15: 73.

Young VB. (2017). “The role of the microbiome in human health and disease: an introduction for clinicians.” BMJ. 356:j831.

Your favorite foods take a wild ride after you take a bite. Picture a go-to snack and consider its journey through your digestive system. Take a ripe, juicy apple, for example. The fruit is full of nutrients for your body to use.

But how does that fruit become usable in your body? After all, your blood isn’t pumping microscopic apples through your arteries and veins. Your body is utilizing the chemical compounds that make apples crunchy and sweet.

Those compounds are extracted from your food through the digestive process. It’s the method by which your diet’s fats, sugars, proteins, fiber, and essential vitamins and minerals—as well as other important nutrients—find their way out of the food you eat to power your body. Digestion also removes waste. And this process is constantly going on in your body.

From dinner plate to elimination, the food you eat takes a long trip through your digestive system. Take a look at the path your food will follow as it is digested:

Mouth >> Esophagus >> Stomach >> Small Intestine >> Large Intestine

At each step along the digestive journey, food is modified and broken down into usable pieces. By modeling this system step-by-step, you can gain a better understanding of the fate of your food after it enters your body.

Learn the Language of Digestion

Before exploring the ins and outs of the digestive system, let’s brush up on the vocabulary. Knowing the words associated with the digestive process will make learning about it a piece of cake.

  • Bolus: chewed food mixed with saliva.
  • Pharynx: throat, the space that links the mouth to the esophagus.
  • Sphincter: ring of muscle that controls passage of liquids and solids from one organ to the next.
  • Chyme: mix of broken-down food and digestive juices that leave the stomach and travel through the small intestine.
  • Villi: microscopic, finger-like projections that cover the walls of the intestine.
  • Bilirubin: pigment released as the result of red blood cell degradation.
  • Stool: waste remaining after digestion.


Eating is by far the most enjoyable part of the digestive process. Your mouth and tongue encounter foods and beverages of all varieties, textures, and tastes. And together, they begin digestion by breaking up the food you eat into small, easy-to-swallow pieces.

You may think digestion begins the moment you take a bite. But in some case, it starts even before that. The sight, smell, or thought of food can be enough to trigger your salivary reflex. That’s why your mouth waters when you’re hungry. Saliva is also produced with the chewing motion. It moistens and lubricates food, making it easier to swallow.

Think of the apple. In the afternoon, when you need something to tide you over until the evening meal, an apple is a great choice. Just thinking of the crunchy fruit and the sweet, tangy, juice can make your mouth water.

The salivary glands in your mouth secrete saliva, which is rich in the digestive enzyme amylase. Salivary amylase breaks apart starches into two-chain sugars called maltose. This simple sugar will later be broken down further into single glucose molecules that can be used as cellular energy.

The movement of the tongue is also important in the digestive process. After food is chewed up and mixed with saliva, it’s ready to be swallowed. Your tongue molds and mashes food into a bolus and guides it to the back of your throat. As you swallow, the bolus of food is pushed through the pharynx and into the esophagus.

Digestive Tract Fact #1 – The salivary glands in your mouth secrete between one and one-and-one-half liters of saliva every day.


Boluses of food are shuttled from the mouth to the stomach via the esophagus. This key connector is guarded by two sphincters at the upper and lower ends. These round muscles act like purse strings that open and close as you swallow.

Each sphincter works independently. The upper esophageal sphincter ushers in boluses from the pharynx. The lower esophageal sphincter empties the contents of the esophagus into your stomach. It can also open to release gas build-up from the stomach. This causes you to belch.

The force that propels food and drink through the esophagus is called peristalsis. The smooth muscles that line the esophagus undergo regular contractions after a bolus is swallowed. The wave-like movement created by peristalsis continues throughout the digestive tract. The motion pushes food through all phases of digestion, in the stomach, small intestine, and large intestine.

Gravity can also aid in moving a meal through your esophagus. By sitting upright, the food you eat can travel swiftly and comfortably down the esophagus and into your stomach.

Digestive Tract Fact #2 – It takes only eight seconds for a bolus of food to travel from the pharynx, through the esophagus, and into the stomach.


As you bite, chew, and swallow, boluses of food are dropped into your stomach. The stomach acts as a storage unit that accepts small packages of food over the course of a meal. A large quantity of food can be quickly stored and then digested over a long period of time.

This is remarkable because, when empty, an adult stomach has a capacity of 75 milliliters. But it can stretch and house up to one liter of food over the course of a meal. That’s over 10 times the starting capacity.

Let’s say you decide to eat more than just an apple. Instead you have yogurt, a turkey sandwich, and some carrots, too. That is a lot of food for your body to store in one sitting. Since your stomach is designed to accommodate full meals, you don’t need to worry about bursting at the seams. Your tummy will take each bite in stride, and process the full meal over the next several hours.

The stomach is a dynamic organ, too. It churns, squeezes, and grinds boluses of food and mixes them with gastric secretions. Peristalsis continues in the stomach and is the driving force for blending food with stomach acid. Stomach secretions help make nutrients available for absorption later in the small intestine.

This digestive juice is powerful hydrochloric acid. It’s strong enough to break apart tightly bound proteins into polypeptide chains (smaller chains of amino acids). It can also eliminate potentially harmful bacteria that may be present in some foods.

Since stomach acid is so potent, its production needs careful supervision. At the start of a meal, gastric function is just starting to warm up and very little stomach acid is secreted. Peristalsis gently begins stretching and squishing the stomach in preparation for incoming food.

In the middle of a meal, peristalsis and stomach acid rev up. Gastric secretions are at an all-time high mid-meal. The muscular stomach is rapidly mixing food and drink with hydrochloric acid. This ensures plenty of fluid in which to break down each bite of food. After food is liquified, it is referred to as chyme.

Peristalsis helps pump chyme into the small intestine while you eat. Once your meal is over, stomach acid secretion comes to a halt. But there may be excess acid. When too much gastric juice remains in the stomach after a meal, irritation of the stomach lining can occur. To protect itself, the stomach adjusts acid production to stay healthy and keep you comfortable.

Stomach contractions continue until all the chyme from the previous meal has entered the small intestine.

Digestive Tract Fact #3 – Stomach rumbles are produced by peristaltic contractions as they move contents through the intestinal tract. They occur during digestion and can continue two hours after the stomach has emptied.

Small Intestine

The small intestine plays the most significant role in the digestive process. And it’s anything but small. At 22 feet (seven meters) long, the small intestine’s primary role is nutrient absorption. Along those 22 feet of digestive “pipe,” several forces combine to optimize small-intestine function.

The lumen (center) of the small intestine is covered in tiny, finger-like tentacles called villi. These densely packed hairs give the mucosa (mucous membrane) of the small intestine a velvety appearance and help their function.

Think of villi like a densely packed carpeting, soaking up every usable nutrient in sight. The purpose of these villi is to increase the surface area of the small intestine. As chyme is further digested, nutrients are absorbed through the villi and transported to the blood stream. A larger surface area means more absorptive space.

Let’s go back to that apple. The fruit-and-stomach-secretion cocktail (chyme) enters the small intestine and mixes with water and other digestive juices like bile. Rhythmic stirring of chyme continues the breakdown of sugars, fats, and proteins from the apple or whatever your previous meal was.

Bile is critical in the digestion of fats into free fatty acids. Bile is composed of water, salts, acids, and lipids. It is a medium in which fats and fat-soluble vitamins can dissolve and be carried into the blood stream via the villi.

Bile also contains bilirubin, a yellow-orange pigment released by red blood cells as they break down. Your body can’t metabolize bilirubin on its own, so it relies on bacteria to help out. When the bacteria in your small intestine chow down on bilirubin, they produce a dark material called sterobilin. This by product gives stool it’s notable brown color.

You also get some help breaking down your food. Microbes in your small intestine do a lot of work to help make fatty acids available for later use. They work alongside secretions from the pancreas (called proteases) that help digest proteins. Proteases break apart complex proteins into peptide chains, then further into individual amino acids.

Now, glucose molecules, amino acids, and free fatty acids are available to be absorbed into the blood stream through the villi.

Digestive Tract Fact #4 – It takes four to five hours for the stomach to completely empty into the small intestine after a meal.

Large Intestine

At end of the journey through the small intestine, most nutrients from digested food have been absorbed. But not everything you eat is an absorbable nutrient. So, what happens to the parts of your food that your body doesn’t need? In the large intestine, undigested material, excess fluids, and mucus all combine to form stool. (There are many more colorful names for it, but stool is the preferred medical term, and what you’ll see moving forward.)

Stool is the solid waste of the digestive process. Believe it or not, your body doesn’t use every particle of food you ingest. Roughage (fiber) travels through the digestive system relatively intact. This is because the digestive enzymes produced in the body cannot break down fiber.

Your snack from earlier, the apple, is a good example of this. The compounds that make the apple skin tough and give the fruit its characteristic crunch pass right through your digestive system with very little nutrient absorption.

Undigested bits of food and fiber accumulate in the large intestine. This final stop on the digestive journey is full of pockets of tissue called haustra. They give the large intestine its puckered appearance. Haustra can stretch to accommodate large amounts of stool as it prepares to leave the body.

The exit of the large intestine and end of the digestive journey—when solid waste is eliminated—is another sphincter called the anus. But in order for stool to leave the digestive tract, it needs a little momentum.

A bowel movement is necessary for your body to expel stool from the large intestine. Very strong peristaltic contractions (the wave-like movements from earlier in the trip through the digestive tract) move stool toward the exit. This creates feelings of pressure in the region and eventually triggers the defecation reflex.

Solid waste is characteristically brown and stinky. You know that bilirubin gives stool its color, but what causes its odor?

If you guessed bacteria are involved, you’re right.

Microbes that reside in the large intestine make a meal of the leftovers from the small intestine. As they interact with stool, gas is created. The smell associated with stool comes from the gases released during the break down of solid waste by bacteria.

Digestive Tract Fact #5 – Stool can sit in the large intestine for up to 48 hours before it is expelled from the body.

Tips for Healthy Digestion

When your digestive system runs smoothly, you feel healthy and comfortable. There are simple ways to keep your tummy in tip top shape.

Let’s start with water.

Ample hydration makes the material in your intestines move easily with each wave of muscle contractions. Drinking plenty of water also helps soften the waste that lurks in your gut. When stool is eventually collected in the rectum, water makes it more comfortable to eliminate.

Fiber also eases digestion.

The complex carbohydrate is bulky and adds weight to stool. Bowel movements are easier to pass when solid waste is heavy. Fiber also absorbs water and softens stool as it travels through the digestive tract. Consider increasing your fiber intake if you notice irregularity in bowel movements. Remember, elimination of solid waste can be different for each person. One study found that normal elimination patterns varied from three times per day to three times per week.

But be careful, adding too much fiber too quickly can have unpleasant consequences. Intestinal gas build-up, bloating, and abdominal discomfort can be the result of ramping up fiber intake too quickly. So, increase the amount of fiber in your diet slowly to maintain intestinal comfort. Look for natural sources of fiber to add to your diet. These include:

  • Fruits
  • Vegetables
  • Nuts
  • Beans
  • Whole grain

Another way to improve digestive health is to take care of the bacteria living in your gut. These microbes do a lot to facilitate healthy digestion. By utilizing probiotics, you can help maintain a healthy balance of intestinal bacteria.

Probiotics support the numbers of helpful microorganisms in your gut. They also aid in nutrient absorption in the small intestine and help break down your food. There is growing evidence to suggest that probiotic supplementation may play a role in supporting immune health, too.

Take a closer look at the digestive system and consider the path your food takes. It is remarkable how your favorite meals are torn apart, liquefied, absorbed, and eventually eliminated by your body. And it’s all to harvest the essential nutrients you need to survive.

So, support your digestive system with lots of water and a high-fiber diet. And make its health (and yours) a priority.

About the Author

Sydney Sprouse is a freelance science writer based out of Forest Grove, Oregon. She holds a bachelor of science in human biology from Utah State University, where she worked as an undergraduate researcher and writing fellow. Sydney is a lifelong student of science and makes it her goal to translate current scientific research as effectively as possible. She writes with particular interest in human biology, health, and nutrition.

A vacation can clear your mind and take the weight of life off your shoulders. But that exotic location, and the journey to get there, could be hard on one part of the body—your gut.

Don’t let that ruin your get-away. There are three steps to ensure your vacation is a happy time for your guts, too.

Step 1: Learn the reasons why travel can impact your gut health will help you plan appropriately.

Step 2: Follow some simple tips to take with you on your next trip.

Step 3: Just like you’d do with your car before a road trip, check out your gut health before you go. Luckily, there’s a simple quiz below to help you out.

Why Travel Can Create Chaos for Your Gut Health

It’s great that the trillions of microbes in your microbiome fly free. But your guts could still pay a price.

Why does this happen? That’s because anytime you travel, you’re accompanied by the frequently fussy passengers in your intestines. And those annoying traveling companions are the reason your gut health can take a hit while you’re on vacation.

This happens because your outside environment plays a role in determining your interior one. What you eat, what you’re exposed to, and the water you drink all impact your microbiome. Feeding your gut bacteria food they aren’t used to can cause chaos—and gastric discomfort. You can also be exposed to foreign bacteria your body doesn’t quite know how to deal with.

Your microbiome is also impacted by jet leg. They have their own rhythm. When these patterns get upset, so do your guts. Your gut microbes could also shape your appetite while you travel. That’s because research has already shown links between the microbiome and systems regulating your hunger levels. This includes hormones and other mechanisms of the brain-gut axis. So, if you get extra hungry on the plane, you might be able to blame your microbiome.

There are other reasons you might experience gut-health issues while you travel—altitude, chaotic schedules, stress, and less-than-ideal dietary habits. But much of it revolves around the contentment of your microbial travel buddies. Keep them happy during your vacation.

Plane taking off through thick clouds.

A Few Quick Gut-Health Tips for Smooth Travel

Being mindful of your microbiome is one of the most important things you can do for your gut health—on vacation or at home. Here are five other simple practices that can help when you travel:

  1. Hydration helps maintain your gut health. And it’s also important to keeping yourself healthy when you’re on-the-go.
  2. Probiotics can support the overall health of your guts by helping to maintain a balance of good bacteria.
  3. If traveling has your guts on lockdown, movement might help get your bowels moving, too.
  4. Plan properly for any situation you might encounter. That means proper vaccinations, bringing the right medicines, and making sure you have healthy foods on hand.
  5. Don’t leave your healthy diet at home. Eating plenty of fiber from whole grains, fruits, and vegetables could help keep your gut bacteria happy—which is key to your happiness, too.

Gut Check! Take the Quiz

Your gut is at the core of your good health. Before you take off on your trip, answer these seven questions to check the state of your digestive health. You can click the plus sign below each question for more information.

  1. How often do you consume high-fiber foods? (fruits, vegetables, beans, oats, nuts, seeds, whole grains)

(3) Frequently

(2) Occasionally

(1) Rarely

Increasing your intake of fiber may not only be good for a flatter tummy. It also can be good inside your belly, too.

Your gut health reflects the quality of your diet. The microflora in your gut will be dominated by different types of bacteria if you eat a diet high in animal fat, versus if you eat a plant-centric, carbohydrate-rich diet. And your diet is the first place to start if you’d like to improve the health of your digestive system. Transitioning to a healthier low-fat, high-fiber diet can start to make notable changes to the environment of your gut in only 24 hours.

A lack of fiber in the diet may lead to progressive declines in some important bacteria and microorganisms in your digestive tract. Whereas, a high-fiber diet (up to 37 grams per day) is thought to feed good bacteria in your gut. Prebiotic foods help the natural bacteria colonies you already have in your gut flourish. Great prebiotic foods to add to your diet: bananas, berries, legumes, onions, garlic, artichokes, leeks, nuts, seeds, and whole grains.


  1. How often do you consume probiotic-containing yogurts/drinks or fermented foods/drinks? (Kefir, kimchee, kombucha, sauerkraut, tempeh, miso, and more.)

(3) Frequently

(2) Occasionally

(1) Rarely

Boosting the beneficial microflora in your gut with probiotics or fermented foods, is a great start in caring for your digestive health. Make sure you look for food and beverages labeled with “live and active cultures.” Remember, heating or other processing can kill the live microorganisms in foods.


  1. Were you breastfed as an infant?

(1) Yes

(0) No

(0) Don’t Know

The method of delivery and the first three years of life are the most important for establishing a healthy diversity of microflora in the gut. Exposure to a wide range of bacteria is key during this time. One important way that parts of the microbiome are transferred is via the mother’s breast milk. Exposure to other family members, pets, a diverse diet, and time in nature are also crucial.


  1. How often do you feel a lot of normal, everyday stress?

(1) Frequently

(2) Occasionally

(3) Rarely

Psychological stress has been associated with weakened gut function when cortisol (a stress hormone) levels also increase. Your gut might be paying the price for normal, everyday stress.


  1. How often do you experience bloating after a meal, gas, or constipation?

(1) Frequently

(2) Occasionally

(3) Rarely

Occasional bloating or gas is normal, but can be uncomfortable. Gas is caused by bacteria in the digestive tract. And how much gas you have can be influenced by swallowed air, what you eat, and the health of your digestive tract. As gas builds up, the abdomen may expand, especially right after eating. This can also be painful … and not just because your clothes start fitting tighter!

You can help beat the belly bloat by avoiding gum chewing, slowing down when you eat, and not drinking out of a straw. Support the normal digestion of high-fiber foods with probiotics and digestive enzymes if certain foods tend to cause gas or bloating. Or, as is the case with lactose intolerance, you may need to identify the culprit and cut it out of your diet.

Occasional constipation is also common and normal. An imbalance of bacteria in your digestive tract is one of the reasons this can happen. It also means your food might not be passing through your system effectively. Maintaining the right balance of microbes will help support the proper function of your digestive tract. Staying hydrated, eating a diet rich in fiber, and getting enough exercise is also important.

(Note: Talk to your doctor about any concerns you have with your digestive system if you answered “frequently” to this question.)


  1. How often do you travel?

(1) Frequently

(2) Occasionally

(3) Rarely

Acute stress during travel can give you an upset tummy. Plus, going to novel environments, particularly overseas destinations, and being exposed to new people increases the risk of exposure to different microbes. Your gut may not know how to respond to the new microbes. Disruptions in your sleep schedule could also alter your intestinal flora.

For more information about travel and gut health, see the rest of the story above.


  1. How much cardiovascular exercise do you get per week?

(1) 0-60 minutes

(2) 61-90 minutes

(3) 91-120 minutes

(4) 121-150 minutes

(5) More than 150 minutes

Chalk up another benefit for exercise. It’s also good for your gut. As your cardiorespiratory fitness improves, you gut microbial diversity also increases.


Add Up Your Answers to Get Your Gut Check Score

Once you’ve totaled the numbers by your responses, see what your gut check score is telling you.



Your Gut Feelings: In Great Shape

Your gut is in great shape! Stay focused on eating a high-fiber diet and foods without antibiotics or other chemicals. And keep your stress in check. If you don’t already, try adding a probiotic supplement to get the most out of your healthy diet. Also, if you plan on traveling soon, a probiotic might help reduce the likelihood of mild and common travelers’ stomach upset.



Your Gut Feelings: Good to Go

You’re taking steps to keep your gut healthy. Way to go! Keep up the good work and take a look at any other improvements you could make:

  • Aim for 150+ minutes of exercise per week.
  • Try adding some fermented foods or more fiber-rich foods to keep feeding your good bacteria.
  • Give a boost to your belly with a probiotic supplement to help maintain overall digestive health.


10 or Below

Your Gut Feelings: Room for Improvement

Your gut may be a little out of balance, so take action today to get your digestive system on the right track. The three most powerful steps that you can take now are:

  • Add more high-fiber foods to your diet.
  • Keep a food journal to identify any food sensitivities. Then reduce or remove those foods from your diet.
  • Try adding a probiotic supplement and/or digestive enzymes to your daily routine to help support digestive health.
defining microbiome

defining microbiome

You’re never alone. Your body is always crawling with trillions of microbial friends. That’s not a bad thing. All of them make up your microbiome—a word you hear a lot, but might not completely understand. Defining microbiome is actually pretty simple. It’s the collection of bacteria, fungi, protozoa, and viruses mentioned above. But don’t let the simple definition fool you. The microbiome is an expansive topic to discuss.

If this is your first time hearing about the microbiome, stay calm. There’s no reason to pull out the sanitizer. You shouldn’t feel gross or unclean. And your skin shouldn’t crawl because you’re an ecosystem for trillions of bacteria and microbes.

The microbiome is a normal part of a healthy life. Many studies suggest that your community of microbes could even play a large role in your health.

If you’re still a little uneasy, an introduction to your microbiome might help. So it’s time to go beyond defining microbiome and introduce you to your bacterial buddies.

A Bit of Basic Bacteria Biology

Other microbes live in your microbiome, but bacteria are the most studied, dominant portion. They’ll mostly be the focus of our attention moving forward. And basic information about bacteria is a great place to start the deeper discussion of the microbiome.

The first thing to know about bacteria—there’s a lot of them. Bacteria rule the earth, even though you can’t see them with your naked eye.

They make up the largest percentage of life on earth. Bacteria weigh more in total than all the humans on earth. One estimate puts the total number of bacteria at about five million trillion trillion. That’s a number so big it doesn’t even have a name. But it’s a five with 30 zeroes after it.

Second, bacteria are in the prokaryote domain. They’re single cells with a primitive outer membrane, no specific cellular parts, and no distinct nucleus. All the ingredients for life—DNA, proteins, and more—float around in the cytoplasm (a cellular liquid).

You fall under a different biological umbrella. Humans, animals, and other complex cellular life belong in the eukaryote domain. That’s because we’re multicellular organisms with membranes around our cellular organelles (cell parts with specific functions) and nuclei.

Your Body and Bacteria

Now that the basic biology is out of the way, it’s time to focus on the bacteria and microbes you interact with. Let’s start with the numbers.

While there’s more bacteria than about anything on earth, that’s not exactly the case with your body. Old estimates had microbiome cells outnumbering yours 10-to-1. Recent research suggest the ratio is closer to 1-to-1. That’s a tenth of what was once thought, but that means you’re still living with trillions of bacteria.

And there’s a great variety of bacteria and microbes inhabiting the communities created by your body. For example, your skin, nose, mouth, ears, and armpits all have very different inhabitants. There is even a difference in who is living between your toes versus other parts of the feet. Your gut—the place our mind goes first when say microbiome—can contain 40,000 different strains and species alone. This diversity is important, because it creates competition for space and food.

Like any lifeform, bacteria are selfish. They don’t live with you because they’re heroes and helpers. Bacteria’s biological imperative is to provide for themselves and their descendants. Luckily, your body has evolved to use the selfishness to its advantage. This creates a win-win situation (symbiosis). The bacteria get food and the body uses compounds produced by the bacteria.

These mostly productive relationships make it easy to think of bacteria as good or bad. That’s an oversimplification of the situation, though. There are some black-and-white cases—pathogenic bacteria that are out to harm you. But the majority of fall into a grey area because most are typically harmless or provide a slight benefit.

How you view specific bacteria (good or bad, healthy or harmful) has a lot to do with location. In one area of the body, a strain of bacteria can be beneficial—aiding in digestion or healthy immune function. In another area, that same type of microbe can cause problems. Sheer numbers can also present issues. For example, a weakened immune system can allow a strain of bacteria to multiply and grow to a population that’s problematic.

And the bacteria don’t suddenly decide to turn from heroes to villains. That’s not how they work. Bacteria act about the same all the time. They’re always selfish. And they’re always trying to multiply. But when they’re in the wrong place—where condition aren’t favorable for symbiosis—or they grow to large numbers, the microbes can wreak havoc.

But if bacteria are mostly harmless, and we shouldn’t call them good or bad, what’s the deal with probiotics? There are certain strains of bacteria that research has shown to provide benefits in certain situations. But in the context of your total bacteria—the trillions of cells and thousands of strains—those are rare, specific cases. That’s why it’s important to get probiotics that are tested and proven to survive in the right bodily environment and demonstrate benefits.

Finding Your Microbiome

Most people hear “microbiome” and think about the gut. Your lower digestive tract is packed with microbes. But it’s not the only place you can find different communities of diverse bacteria.

Let’s go through them:

  • Gut: Your stomach doesn’t contain much bacteria. High acidity creates an uninviting environment where few can survive. Your intestines are a different story—mostly because that’s where food stays for the longest time. The gut microbiome has been extensively studied, so we can name many of the bacterial categories you’d find in your intestines.
  • Both the small and large intestines are packed full of a variety of microbes, but Bacteriodetes (another category of bacteria) are very prevalent. And you’ll find distinct populations of bacteria in the small intestine and the large intestine, with different strains dominating each.
  • Skin: Your body’s largest organ has its own community of bacteria and microbes. If you’re a germaphobe, this confirms your worst fears. You really are covered with bacteria. All the folds, nooks, and crannies of your skin provide ample space to develop diverse microbial communities. Remember, the vast majority are harmless in normal circumstances. And most of them can be categorized as Actinobacteria (a category of bacteria).
  • Mouth: Your teeth, tongue, cheek, lips, and palate provide habitat for mostly harmless or beneficial bacteria. Almost 300 different species have been found in the mouth alone. And those are just the ones that have names so far.
  • Ear, Nose, Sinuses, and Throat: Each of these regions contains bacteria that can thrive in that particular environment. But they’re mentioned together because they’re all connected. And they intersect with the mouth, as well.

This is not a comprehensive list of your body’s bacterial communities. They’re in your sex organs, lungs, and about any hospitable place they can find. The gut gets most of the attention, but researchers are looking more closely at other areas. That research will help us get to know our microbiomes better, and help us meet more of our bacterial buddies.

The Making of a Microbiome

You’re shaped by the ecosystem in which you live. Your microbiome is the same. But in this case, you’re the ecosystem.

That’s why everyone’s microbiome is unique. Yours is shaped by the experiences you have—starting at birth. Natural birth or Caesarean section will impact an infant’s microbiome. Your diet and environment impact your body and the bacterial friends that live with you. Age is also an important differentiating factor.

With the array of variables and huge variety of bacteria in your body’s ecosystem, it’s difficult to identify every strain of bacteria “normal” or “healthy” people will have. Mapping out your specific microbiome regularly over time is time consuming and overwhelming. And doing it once doesn’t tell you much. But talking more generally provides the information you need without listing thousands of bacterial strains.

Basically, the bacteria that coexist with you are the ones able to find a biological niche. They’re best able to adapt and survive in your specific conditions. In this way, you’re somewhat in control of your microbiome. And somewhat is the keyword. It’s not as easy as selecting your preferred bacteria, because you can’t control everything. We do know that good habits— sleeping well, exercising, and eating a healthy diet—encourage a beneficial microbiome.

But bacteria are living things. They’re competing with trillions of others for space and food. You can influence the results of this competition, but you can’t totally fix the game. And for those same reasons, your microbiome is constantly changing.

What Can the Microbiome Do for You?

The simple answer—your microbiome does a lot. And research is revealing more and more about what it does for you and your health.

This example tells you quite a bit: Mice raised without a community of bacteria—born and raised in a sterile environment—don’t exhibit the same type of growth as mice with a microbiome. Germ-free mice also show deficiencies in behavior and other health issues not seen in normal mice.

In general, your microbiome helps with digestive processes, immune function, maintaining a healthy weight, nervous system function, and more. But that’s another story. You can dive deeper into the ways your bacterial buddies help out your health in the next article in our microbiome series.